1) Field of the Invention
The present invention relates generally to the field of pipe cleaning apparatus and, more particularly, to plug assemblies used to clean heat exchanger and condenser tubing or piping.
2) Description of the Prior Art
Many heat exchangers utilize water passing through tubes. Water sources passing through the tubes present many problems, such as deposits and obstructions, that limit the heat transfer and life expectancy of the tubing. Slime, sticks, mud, shells, calcium carbonate scale or manganese scale are examples of problems.
Pipe cleaning assemblies have been developed to aid in the removal of the obstructions and deposits. Typically, these pipe cleaning assemblies include a fin or blade arrangement attached to a body. The pipe cleaning assembly is placed at one end of the tube to be cleaned with the fins in contact with an inner surface of the tube. High pressure water or other liquid is applied to the tube and passes the pipe cleaning assembly through the tube, scraping the inner surface and removing obstructions and deposits along the way until the pipe cleaning assembly exits the tube.
The pipe cleaning assemblies can be made from a polymeric material, such as the FLEX-DART.TM. pipe cleaning assembly manufactured by ITC, Inc., the assignee of this patent application. For more difficult deposits, a metal fin can be used, such as the stainless steel DART.TM. pipe cleaning assembly manufactured by ITC, Inc., the assignee of this patent application, and shown in FIG. 1.
Specifically, FIG. 1 shows a prior art stainless steel DART.TM. pipe cleaning assembly 10 that includes a unitary plastic body 12 having a plurality of stamped metal scraper blades 14 removably attached thereto. The metal scraper blades 14 include an engagement portion 16 and a scraping blade portion 18. Legs 20 connect the scraping blade portion 18 to the engagement portion 16. Windows 22 are defined by the legs 20. The scraping blade leg portion 18 is defined by three arcuate segments 24 of approximately 90.degree. and results in a non-continuous member with a body receiving opening 26. Finally, a tip 28 and a tail piece 30 are provided on the body 12.
Preferably, three metal scraper blades 14 are received by the body 12. The metal scraper blades 14 are axially spaced apart from each other and circumferentially offset so that the pipe cleaning assembly 10 contacts the complete periphery of the inner surface of the pipe as it is pushed through the tube.
Although the pipe cleaning assembly 10 works well, it must be preassembled which requires a substantial amount of labor costs. Also, the length of the pipe cleaning assembly 10 is limited by the length of the body 12. Furthermore, the metal scraper blades 14 are expensive to manufacture because of their non-circular shape that results in a high rejection rate. Furthermore, the pipe cleaning assembly 10 cannot be repaired in the field.
Therefore, it is an object of the present invention to provide a pipe cleaning assembly that can be assembled and repaired in the field and is inexpensive to manufacture.